1. Field of the Invention
The present invention relates to an optical device making it possible to recover the timing (also known as clock) of a signal coded by a digital code. It has numerous applications in the field of data transmission by optical fibres.
2. Brief Description of Related Art
In most digital transmission systems, it is necessary to be able to resynchronize, on reception, the information signal transmitted in digital form in order to read the information contained therein. Numerous electronic devices able to recover the timing of the information signal (i.e. the clock of the coded signal which they receive) are known. However, when the transmission system is of the optical type (transmission by optical fibres), it is often important to ensure the optical continuity in the system. It is then necessary to use an optical timing recovery device.
The document by D. J. AS, R. EGGEMANN et al entitled "Clock recovery based on a new type of selfpulsation in a 1.5 .mu.m two-section InGaAsP-InP DFB laser", published in Electronics Letters, 21.1.1991, vol. 29, No. 2 describes such an optical timing recovery device. This device, which uses feedback laser diodes, suffers from the main disadvantage of only permitting timing recovery on the basis of signals coded by the RZ (return to zero) code for which each information bit (bit in state 1) of the signal has a duration equivalent to a half clock cycle.